It is generally accepted that stars produce most of the light in the universe, while planets, satellites, dust and gas reflect it. However, it turned out that the stars also reflect light - we did not notice this before, since the amount of this reflected light is negligible.
The source of this conclusion was a new study of twin stars located in a reciprocal spiral orbit, each of which reflects a small amount of light from the other. The main object of study of astronomers has become Spica - a system of two stars that are located at a distance of about 250 light-years in the constellation Virgo and rotate relative to each other with a period of about four days. The results of scientists are published in the journal Nature Astronomy.
Through work and observation, a team of astronomers from the University of New South Wales in Australia found that the polarization of light, or the orientation of its wave, changes depending on the orbits of two stars. Light that travels directly is not polarized and vibrates in several planes at the same time. When it reflects off a non-metallic surface, it becomes polarized and vibrates in only one plane. While observing the polarized light emanating from the binary star, experts recorded a reflection, so they resorted to computer models to refine the data.
“We were able to determine that the amount of polarization we observed was exactly the same as predicted by the reflected light model. Our simulations have shown that stars actually reflect light rather poorly. For example, the Sun reflects less than 0.1 percent of the incident light. However, for hotter stars, such as the components of the Spica star, with temperatures from 20 to 25 thousand Kelvin, this figure rises to several percent. But the total amount of reflected light coming from this system is still quite small,”says physicist Jeremy Bailey of the University of New South Wales.
According to the researchers, the total amount of reflected light is only a few percent of the incident light, but it can be easily recognized because it is extremely polarized. As part of the study, scientists have developed their own high-precision polarimeters, thus adding a new tool to the existing set of methods for detecting binary stars. Thus, the orbits of stars in a binary system are located very close to each other, and therefore it is impossible to separate them optically. However, they will still reflect each other's light, so it is with the help of polarization that you can find out that the system is binary.
In addition, the new method may help to find out some details about binary star systems. For example, the polarization of the Spica system showed that it was moving clockwise, confirming previous results. In addition, as Bailey noted, the method can be used to determine the mass of binary stars.
However, the method will not be so useful when studying single stars, because they, as a rule, are rarely located close enough to another light source. Any light that they reflect comes from far away, it is simply not enough to detect and use. However, most stars (about 85 percent) have binary satellites: astronomers believe that most, if not all, stars are born in pairs, but some lose twins over time. This means that the study of binary pairs can actually be very important for the study of stars in general. The team of scientists will apply and test their method on other binary stars.